Vehicle manufacturers, tire manufacturers and road authorities are striving to reduce low road friction at winter times. The actual road friction is the result not only of the present road conditions but is also affected by the quality of the tires on the vehicle. Inadequate tire friction performance is a serious contributor to insufficient road friction, especially at winter times. No matter how high quality a set of new tires has when a new vehicle is delivered to the first customer, tires will eventually be worn down as mileage is added and tire friction performance may gradually be degraded.
Another potential problem is that a vehicle, that is originally equipped with tires with high road friction quality, selected by the vehicle manufacturer as a part of the vehicle design process, might later be equipped with tires of lower quality and with lower friction performance. In such cases, despite the set of tires being brand new, tire friction performance may still be inferior as compared to high quality tires—in this case, new tires with low friction performance could potentially be deceptive to the driver that is likely to assume that a new set of tires should imply good friction performance.
Since tires will typically be replaced a number of times during the life length of a vehicle, it is not unlikely that some drivers may be unaware of how the set of tires that is mounted on their car actually performs (compared to the unused high performing tires that was originally mounted on the car).
Empirical tests of winter tires have shown that the road friction quality can be very different between tires of different brands; there is indeed a difference in tire quality with respect to road friction performance.
The problem also extends to the usage of “all-weather”, “all-season” or “all-year-round” tires in areas with changing weather seasons (e.g., both summer and winter seasons), where the same set of tire often does not have the capacity to deliver sufficient friction performance though the changing weather conditions throughout the whole year. The marketing of “all-year-round” tires may mislead drivers to an incorrect perception that the tires on their vehicle have sufficient friction performance in both summer and winter conditions, since the drivers might be unaware of the relatively low friction performance of their tires as compared to other high performing season tires (i.e., summer and winter tires) that are designed for optimal performance on the more specific road conditions that are typical for either winter or summer.
In view of the above, there is a need to estimate the quality of the tires of a vehicle, so as to determine the tires ability to provide sufficient road friction.
WO2012/158888 describes a method for performing a field survey including a large amount of data relating to tires. The tire data collected includes tire pattern, tire brand and serial number, tire position in the vehicle, tire option code, air pressure, mounting date, etc. Moreover, tire wear information such as depth, width and length of irregular thread wear is collected. The information collected may be used for estimating e.g., how many more miles a tire may safely drive. The tire data may be collected e.g., during a planned service of the vehicle.
Although the method described in WO2012/158888 might be useful for estimating certain qualities with tires which may have an impact on their ability to provide sufficient road friction, it lacks a possibility of evaluating how the tires perform in real-life conditions.
Accordingly, there is still a need to provide an improved method for estimating the quality of the tires of a vehicle.